Fungi are ubiquitous worldwide, and inconspicuous as they are most commonly microscopically small. Mycotoxins are secondary metabolites secreted by fungi. Mycotoxins are toxic and/or carcinogenic compounds produced by various fungal species that grow on various agricultural commodities. Examples of mycotoxins, include but are not limited to aflatoxins, fumonisins, ochratoxin A, deoxynivalenol (a.k.a. “DON” or “vomitoxin”), patulin, and zearalenone. Myotoxins are often produced in cereal grains as well as forages before, during and after harvest. Some mycotoxins are lethal, some cause identifiable diseases or health problems, some weaken the immune system without producing symptoms specific to that mycotoxin, some act as allergens or irritants, and some have no known effect on animals or humans. The greatest economic impact of mycotoxin contamination is felt by crop and poultry producers, as well as food and feed producers. Mycotoxins can appear in the food chain as a result of fungal infection of plant products, and can either be eaten directly by humans, or introduced by contaminating livestock feedstuff(s). Mycotoxins contaminate organic materials (e.g. bedding) as well as water, and greatly resist decomposition during digestion so they remain in the food chain in edible products (e.g. meat, eggs and dairy products). No region of the world escapes mycotoxins and their negative impact on animal and human health. The evolution of global trading of feedstuffs increases the chances that blends of grains will result in combinations of mycotoxins in a given diet and that unusual and unsuspected mycotoxins will be present in a given region regardless of its climate condition.
Strategies used to avoid mycotoxin occurrence involve controlling elements that permit mycotoxin production, controlling mold growth, as well as practicing quality control of food and feeds via adequate sampling, detection and quantification methodology. However, mycotoxin contamination is unavoidable.
In order to reduce the negative effects of mycotoxins, inorganic materials such as clays, bentonites, and aluminosilicates, known for their adsorptive properties, have historically been added to feedstuffs. Feedstuff-additives, in large quantities, sequester some mycotoxins in the gastrointestinal tract of the animal and minimize their toxic effects. However, additives hinder the absorption of many beneficial nutrients that are important to animals such as vitamins, minerals, and amino acids thereby decreasing the nutrient density of the diet. Moreover, feedstuff additives, particularly in animal feces, have an extremely detrimental environmental impact.
Chemical agents such as acids, bases (e.g., ammonia, caustic soda), oxidants (e.g., hydrogen peroxide, ozone), reducing agents (e.g., bisulphites), chlorinated agents and formaldehyde, have been used to degrade mycotoxins in contaminated feeds, particularly aflatoxins (See, e.g., Hagler 1991; Phillips et al 1994; Lemke et al 2001). However, these techniques are not efficient, are expensive, generate a significant amount of chemical waste, and are generally unsafe.
Certain strains of lactic acid bacteria, propionibacteria and bifidobacteria have cell wall structures that bind mycotoxins (See, e.g., Ahokas et al 1998; El-Nemazi et al 1998; Yoon et al 1999) and limit their bioavailability in the animal body. However, these biological processes are generally slow, produce toxic metabolites, and are inefficient.